Flexible bandwidth demands of data center applications, mobile backhaul, and broadband Internet access are driving telecom service providers to investigate more direct use of connection-oriented packet transport technologies in their traditional circuit-based optical transport networks. Carrier-grade packet transport technologies including Multi-Protocol Label Switching-Transport Profile (MPLS-TP), provider bridge (PB), provider-based bridge (PBB), and provider-based bridge traffic engineering (PBB-TE) are becoming mature and have been deployed in metro area networks (MANs). Today, most traffic flows are in Ethernet format and typically transported at a single layer, a packet layer, for example, in an Ethernet virtual circuit (EVC) or MPLS label-switched-path (LSP), or a circuit layer, for example, in an optical transport network (OTN), synchronous digital hierarchy (SDH), or directly over lambda through digital wrapper technologies, which results in higher cost and lower efficiency. With the integration of packet and optical transport, a network can adaptively transport services over the most efficient layer for different types of traffic flows, not just the pre-defined transport technology. For example, a switched Ethernet service could traverse the network partially over OTN and then over MPLS-TP before being handed off as Ethernet, if that were most efficient.
Packet transport and optical transport have been brought into one network element (NE) for carrying various types of traffic flows. Architecturally, each NE can contain multiple units including Ethernet/MPLS-TP for data packets, OTN/SDH for time-division multiplexing (TDM), and lambda fabrics. For the interface cards, hybrid OTN/Ethernet/MPLS-TP line interfaces have been developed. Moreover, the logically centralized network controller such as path-computation-entity (PCE) and software-defined-network (SDN) have been proposed recently to evaluate all layers of the network intelligently to determine which layer is the best to transport traffic flows. This enables the seamless integration of packet and optical transport network for the application flows. The packet optical combination can create the most efficient transport solution for a given mixed TDM/packet traffic flows matrix, but it depends on how packet optical transport resources will be effectively dimensioned in advance. To maximize the gains of optical bypass introduced by optical transport and statistical multiplexing introduced by packet transport, an advanced network planning and design system is necessary, designed with enough foresight into bandwidth growth to be able to meet future needs with existing infrastructure. The network planning and design system is particularly useful in metro area networks and the core of the network, whereby particular network optimization techniques can be used to minimize the total number of network element ports need to be added to satisfy the explosion of bandwidth usage.